// Gingerbread Man
//
// A dot constellation that is generated procedurally by an
// Iterated function system (IFS).
//
// The IFS:
// x = R(1 + 2S) - old_y + abs(old_x - SR)
// y = old_x
//
// The pattern is familiar with the chaos theory as it is
// a form of a strange attractor

#include <windows.h>
#include <gl/gl.h>
#include <gl/glu.h>

HGLRC		hRC=NULL;									// Permanent Rendering Context
HDC			hDC=NULL;									// Private GDI Device Context
HWND		hWnd=NULL;									// Holds Our Window Handle
HINSTANCE	hInstance;									// Holds The Instance Of The Application

bool	keys[256];										// Array Used For The Keyboard Routine
bool	active=TRUE;									// Window Active Flag Set To TRUE By Default
bool	fullscreen=TRUE;								// Fullscreen Flag Set To Fullscreen Mode By Default

LRESULT	CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);	// Declaration For WndProc

GLvoid ReSizeGLScene(GLsizei width, GLsizei height)		// Resize And Initialize The GL Window
{
	if (height==0)										// Prevent A Divide By Zero By
	{
		height=1;										// Making Height Equal One
	}

	glViewport(0, 0, width, height);					// Reset The Current Viewport

	glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix
	glLoadIdentity();									// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix
	glLoadIdentity();									// Reset The Modelview Matrix
}

int InitGL(GLvoid)										// All Setup For OpenGL Goes Here
{
	glShadeModel(GL_SMOOTH);							// Enables Smooth Shading

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);				// Black Background
	glColor3f(1,1,1);									// White colour for points

	glClearDepth(1.0f);									// Depth Buffer Setup
	glEnable(GL_DEPTH_TEST);							// Enables Depth Testing
	glDepthFunc(GL_LEQUAL);								// The Type Of Depth Test To Do

	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	// Really Nice Perspective Calculations

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	// Clear screen to background colour

	glPointSize(1.0);									// Set the point size to 3 pixels

	return TRUE;										// Initialization Went OK
}

int DrawGLScene(GLvoid)									// Here's Where We Do All The Drawing
{
	// Don't bother clearing screen

	glLoadIdentity();
	glTranslatef(-30,-30,-90);							// Translate out a so we can see the image and adjust image to middle of screen
	glScaled(0.15, 0.15, 0.15);							// Fit image on screen

	float x, y;											// x/y of point to draw
	static float old_x=115, old_y=121;					// Previous point
	static float R=40, S=3;								// Constant Values

	glBegin(GL_POINTS);
		for (int i=0; i<1000; i++)						// Draw 1000 points per render
		{
			x = R*(1 + 2*S) - old_y + abs(int(old_x - S*R));// The IFS for x
			y = old_x;										// and for y

			old_x = x;
			old_y = y;

			glVertex2f(x,y);							// Output that magic vertex
		}
	glEnd();

	glFlush();											// Flush the OpenGL pipe

	return TRUE;										// Everything Went OK
}

GLvoid KillGLWindow(GLvoid)								// Properly Kill The Window
{
	if (fullscreen)										// Are We In Fullscreen Mode?
	{
		ChangeDisplaySettings(NULL,0);					// If So Switch Back To The Desktop
		ShowCursor(TRUE);								// Show Mouse Pointer
	}

	if (hRC)											// Do We Have A Rendering Context?
	{
		if (!wglMakeCurrent(NULL,NULL))					// Are We Able To Release The DC And RC Contexts?
		{
			MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}

		if (!wglDeleteContext(hRC))						// Are We Able To Delete The RC?
		{
			MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		}
		hRC=NULL;										// Set RC To NULL
	}

	if (hDC && !ReleaseDC(hWnd,hDC))					// Are We Able To Release The DC
	{
		MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hDC=NULL;										// Set DC To NULL
	}

	if (hWnd && !DestroyWindow(hWnd))					// Are We Able To Destroy The Window?
	{
		MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hWnd=NULL;										// Set hWnd To NULL
	}

	if (!UnregisterClass("OpenGL",hInstance))			// Are We Able To Unregister Class
	{
		MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
		hInstance=NULL;									// Set hInstance To NULL
	}
}

BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
	GLuint		PixelFormat;							// Holds The Results After Searching For A Match

	WNDCLASS	wc;										// Windows Class Structure

	DWORD		dwExStyle;								// Window Extended Style
	DWORD		dwStyle;								// Window Style

	RECT WindowRect;									// Grabs Rectangle Upper Left / Lower Right Values
	WindowRect.left=(long)0;							// Set Left Value To 0
	WindowRect.right=(long)width;						// Set Right Value To Requested Width
	WindowRect.top=(long)0;								// Set Top Value To 0
	WindowRect.bottom=(long)height;						// Set Bottom Value To Requested Height

	fullscreen=fullscreenflag;							// Set The Global Fullscreen Flag

	hInstance		= GetModuleHandle(NULL);			// Grab An Instance For Our Window
	wc.style		= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;	// Redraw On Move, And Own DC For Window
	wc.lpfnWndProc		= (WNDPROC) WndProc;			// WndProc Handles Messages
	wc.cbClsExtra		= 0;							// No Extra Window Data
	wc.cbWndExtra		= 0;							// No Extra Window Data
	wc.hInstance		= hInstance;					// Set The Instance
	wc.hIcon		= LoadIcon(NULL, IDI_WINLOGO);		// Load The Default Icon
	wc.hCursor		= LoadCursor(NULL, IDC_ARROW);		// Load The Arrow Pointer
	wc.hbrBackground	= NULL;							// No Background Required For GL
	wc.lpszMenuName		= NULL;							// We Don't Want A Menu
	wc.lpszClassName	= "OpenGL";						// Set The Class Name

	if (!RegisterClass(&wc))							// Attempt To Register The Window Class
	{
		MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Exit And Return FALSE
	}

	if (fullscreen)										// Attempt Fullscreen Mode?
	{
		DEVMODE dmScreenSettings;						// Device Mode
		memset(&dmScreenSettings,0,sizeof(dmScreenSettings)); // Makes Sure Memory's Cleared
		dmScreenSettings.dmSize=sizeof(dmScreenSettings); // Size Of The Devmode Structure
		dmScreenSettings.dmPelsWidth	= width;		// Selected Screen Width
		dmScreenSettings.dmPelsHeight	= height;		// Selected Screen Height
		dmScreenSettings.dmBitsPerPel	= bits;			// Selected Bits Per Pixel
		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;

		// Try To Set Selected Mode And Get Results.  NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.
		if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
		{
			// If The Mode Fails, Offer Two Options.  Quit Or Run In A Window.
			if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
			{

				fullscreen=FALSE;						// Select Windowed Mode (Fullscreen=FALSE)
			}
			else
			{
				// Pop Up A Message Box Letting User Know The Program Is Closing.
				MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);
				return FALSE;							// Exit And Return FALSE
			}
		}
	}

	if (fullscreen)										// Are We Still In Fullscreen Mode?
	{
		dwExStyle=WS_EX_APPWINDOW;						// Window Extended Style
		dwStyle=WS_POPUP;								// Windows Style
		ShowCursor(FALSE);								// Hide Mouse Pointer
	}
	else
	{
		dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;	// Window Extended Style
		dwStyle=WS_OVERLAPPEDWINDOW;					// Windows Style
	}

	AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);	// Adjust Window To True Requested Size

	if (!(hWnd=CreateWindowEx(	dwExStyle,				// Extended Style For The Window
					"OpenGL",							// Class Name
					title,								// Window Title
					WS_CLIPSIBLINGS |					// Required Window Style
					WS_CLIPCHILDREN |					// Required Window Style
					dwStyle,							// Selected Window Style
					0, 0,								// Window Position
					WindowRect.right-WindowRect.left,	// Calculate Adjusted Window Width
					WindowRect.bottom-WindowRect.top,	// Calculate Adjusted Window Height
					NULL,								// No Parent Window
					NULL,								// No Menu
					hInstance,							// Instance
					NULL)))								// Don't Pass Anything To WM_CREATE
	{
		KillGLWindow();									// Reset The Display
		MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Return FALSE
	}

	static	PIXELFORMATDESCRIPTOR pfd=					// pfd Tells Windows How We Want Things To Be
	{
		sizeof(PIXELFORMATDESCRIPTOR),					// Size Of This Pixel Format Descriptor
		1,												// Version Number
		PFD_DRAW_TO_WINDOW |							// Format Must Support Window
		PFD_SUPPORT_OPENGL |							// Format Must Support OpenGL
		PFD_DOUBLEBUFFER,								// Must Support Double Buffering
		PFD_TYPE_RGBA,									// Request An RGBA Format
		bits,											// Select Our Color Depth
		0, 0, 0, 0, 0, 0,								// Color Bits Ignored
		0,												// No Alpha Buffer
		0,												// Shift Bit Ignored
		0,												// No Accumulation Buffer
		0, 0, 0, 0,										// Accumulation Bits Ignored
		16,												// 16Bit Z-Buffer (Depth Buffer)
		0,												// No Stencil Buffer
		0,												// No Auxiliary Buffer
		PFD_MAIN_PLANE,									// Main Drawing Layer
		0,												// Reserved
		0, 0, 0											// Layer Masks Ignored
	};

	if (!(hDC=GetDC(hWnd)))								// Did We Get A Device Context?
	{
		KillGLWindow();									// Reset The Display
		MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Return FALSE
	}

	if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))		// Did Windows Find A Matching Pixel Format?
	{
		KillGLWindow();									// Reset The Display
		MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Return FALSE
	}

	if(!SetPixelFormat(hDC,PixelFormat,&pfd))			// Are We Able To Set The Pixel Format?
	{
		KillGLWindow();									// Reset The Display
		MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Return FALSE
	}

	if (!(hRC=wglCreateContext(hDC)))					// Are We Able To Get A Rendering Context?
	{
		KillGLWindow();									// Reset The Display
		MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Return FALSE
	}

	if(!wglMakeCurrent(hDC,hRC))						// Try To Activate The Rendering Context
	{
		KillGLWindow();									// Reset The Display
		MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Return FALSE
	}

	ShowWindow(hWnd,SW_SHOW);							// Show The Window
	SetForegroundWindow(hWnd);							// Slightly Higher Priority
	SetFocus(hWnd);										// Sets Keyboard Focus To The Window
	ReSizeGLScene(width, height);						// Set Up Our Perspective GL Screen

	if (!InitGL())										// Initialize Our Newly Created GL Window
	{
		KillGLWindow();									// Reset The Display
		MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;									// Return FALSE
	}

	return TRUE;										// Success
}

LRESULT CALLBACK WndProc(	HWND	hWnd,				// Handle For This Window
				UINT	uMsg,							// Message For This Window
				WPARAM	wParam,							// Additional Message Information
				LPARAM	lParam)							// Additional Message Information
{
	switch (uMsg)										// Check For Windows Messages
	{

		case WM_ACTIVATE:								// Watch For Window Activate Message
		{
			if (!HIWORD(wParam))						// Check Minimization State
			{
				active=TRUE;							// Program Is Active
			}
			else
			{
				active=FALSE;							// Program Is No Longer Active
			}

			return 0;									// Return To The Message Loop
		}


		case WM_SYSCOMMAND:								// Intercept System Commands
		{
			switch (wParam)								// Check System Calls
			{
				case SC_SCREENSAVE:						// Screensaver Trying To Start?
				case SC_MONITORPOWER:					// Monitor Trying To Enter Powersave?
				return 0;								// Prevent From Happening
			}
			break;										// Exit
		}

		case WM_CLOSE:									// Did We Receive A Close Message?
		{
			PostQuitMessage(0);							// Send A Quit Message
			return 0;									// Jump Back
		}

		case WM_KEYDOWN:								// Is A Key Being Held Down?
		{
			keys[wParam] = TRUE;						// If So, Mark It As TRUE
			return 0;									// Jump Back
		}

		case WM_KEYUP:									// Has A Key Been Released?
		{
			keys[wParam] = FALSE;						// If So, Mark It As FALSE
			return 0;									// Jump Back
		}

		case WM_SIZE:									// Resize The OpenGL Window
		{
			ReSizeGLScene(LOWORD(lParam),HIWORD(lParam)); // LoWord=Width, HiWord=Height
			return 0;									// Jump Back
		}
	}

	// Pass All Unhandled Messages To DefWindowProc
	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(	HINSTANCE	hInstance,				// Instance
			HINSTANCE	hPrevInstance,					// Previous Instance
			LPSTR		lpCmdLine,						// Command Line Parameters
			int		nCmdShow)							// Window Show State
{

	MSG	msg;											// Windows Message Structure
	BOOL	done=FALSE;									// Bool Variable To Exit Loop

	// Ask The User Which Screen Mode They Prefer
	if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
	{
		fullscreen=FALSE;								// Windowed Mode
	}

	// Create Our OpenGL Window
	if (!CreateGLWindow("Project",640,480,16,fullscreen))
	{
		return 0;										// Quit If Window Was Not Created
	}

	while(!done)										// Loop That Runs Until done=TRUE
	{
		if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))		// Is There A Message Waiting?
		{
			if (msg.message==WM_QUIT)					// Have We Received A Quit Message?
			{
				done=TRUE;								// If So done=TRUE
			}
			else										// If Not, Deal With Window Messages
			{

				TranslateMessage(&msg);					// Translate The Message
				DispatchMessage(&msg);					// Dispatch The Message
			}
		}
		else											// If There Are No Messages
		{
			// Draw The Scene.  Watch For ESC Key And Quit Messages From DrawGLScene()
			if (active)									// Program Active?
			{
				if (keys[VK_ESCAPE])					// Was ESC Pressed?
				{
					done=TRUE;							// ESC Signalled A Quit
				}
				else									// Not Time To Quit, Update Screen
				{
					DrawGLScene();						// Draw The Scene
					SwapBuffers(hDC);					// Swap Buffers (Double Buffering)
				}
			}
			if (keys[VK_F1])							// Is F1 Being Pressed?
			{
				keys[VK_F1]=FALSE;						// If So Make Key FALSE
				KillGLWindow();							// Kill Our Current Window
				fullscreen=!fullscreen;					// Toggle Fullscreen / Windowed Mode
				// Recreate Our OpenGL Window
				if (!CreateGLWindow("Project",640,480,16,fullscreen))
				{
					return 0;							// Quit If Window Was Not Created
				}
			}
		}
	}
	// Shutdown
	KillGLWindow();										// Kill The Window
	return (msg.wParam);								// Exit The Program
}


















